The invention relates to an apparatus and method for testing and measuring viscoelastic solids, including their ability to withstand stress and strain. An example of a use for the invention is to test tire cord used for reinforcing pneumatic tires.
An earlier design of an apparatus related to the present invention is disclosed in U.S. Pat. No. 3,893,331 filed Apr. 26, 1973 and entitled "Method and Apparatus for Determining Side Wall Temperature in Running Tires". U.S. Pat. application Ser. No. 528,610 filed Dec. 2, 1974 now U.S. Pat. No. 3,934,452 and entitled "Method of Determining Dynamic Strain in Composite Structures" discloses that viscoelastic properties, moduli E' and E" and tan .delta. vary cyclically during the cyclic straining of cords. Toyo Measuring Instruments Co., Ltd. of Tokyo, Japan manufactures an apparatus known as a "Direct Reading Dynamic Viscoelastometer" and by the name "VIBRON" which differs in structure and operation from the present invention. Conventional linear viscoelastic theory is disclosed in "Viscoelastic Properties of Polymers," by John D. Ferry, published by John Wiley & Sons, Inc., 1970, particularly pages 12 and 606-609. Other testing apparatus are disclosed in U.S. Pat. No. 1,558,594 to Coffin and in the Journal of Applied Physics, Vol. 18, June 1947, page 586; Vol. 17, August 1946, page 699; and Vol. 16, July 1945, page 398.